The effect of secretory immunoglobulin A on the in-vitro adherence of the yeast Candida albicans to human oral epithelial cells

Secretory immunoglobulin A (s-IgA) isolated from human breast milk inhibited the adherence of C. albicans to human oral epithelial cells. This inhibitory effect of s-IgA was maximal at $\text{1}\text{1}\text{2}$ hours, it was concentration-dependent and was still detectable at subagglutinating antibody concentrations. The inhibitory action of s-IgA was due to its content of specific candidal antibody. Non-specifically bound s-IgA enhanced adherence of the yeast and presumably tends to impair the immune disposal of Candida by specific antibody. The reduced adherence of candida pre-treated with 0.4 per cent formol saline at a concentration which kills the organism but leaves its surface antigens intact suggests that, although dead organisms may form an initial loose attachment to the epithelial surface, only viable organisms bind irreversibly. The specific-s-IgA appears to block surface sites on C. albicans involved in epithelial adherence but this action of s-IgA cannot be attributed solely to its agglutinating properties.